WO2025037292A1

WO2025037292A1 - A wheeled work vehicle

Info

Publication number: WO2025037292A1
Application number: PCT/IE2024/000009
Authority: WO
Inventors: James Mcadam; Samuel HAMPSHIRE
Original assignee: Multihog R& D Ltd
Current assignee: Multihog R& D Ltd
Priority date: 2023-08-16
Filing date: 2024-08-16
Publication date: 2025-02-20
Anticipated expiration: 2026-02-16

Abstract

A wheeled work vehicle (1) comprising a chassis (3) and a mower (2) mounted on and beneath the chassis (3). A pair of rear main ground engaging wheels (9) are carried on trailing suspension arms (34) pivotally coupled to the chassis (3) about a main transverse pivot axis (38). A pair of spaced apart ground engaging castor wheels (10) are located adjacent a forward end (5) of the chassis (3). Electrically powered main drive motors (50) are carried on the trailing suspension arms (34) for driving the corresponding rear main ground engaging wheels (9). Each main drive motor (50) is of transverse cross-section less than the internal transverse cross-section of wheel wells (30) of the corresponding rearward ground engaging wheels (9) so that the main drive motors (50) are located in the wheel wells (30) of the respective rearward ground engaging wheels (9) for minimising the overall width of the work vehicle (1).

Description

A wheeled work vehicle

The present invention relates to a wheeled work vehicle.

Wheeled work vehicles are well known, and in general, are powered by internal combustion engines. However, it is known to electrically power wheeled work vehicles, and in such cases, such wheeled work vehicles are electrically powered from a rechargeable battery. However, such wheeled work vehicles tend to be rather large and cumbersome, irrespective of whether they are powered by an internal combustion engine or electrically powered by a rechargeable battery, and typically, are relatively large and cumbersome and not easily manoeuvrable for use in mowing grass, particularly, for use in mowing areas of grass of areas of the type which would normally be found in public parks, football pitches, golf courses and the like. Accordingly, there is a need for a wheeled work vehicle, suitable for mowing grass which is less cumbersome and more easily manoeuvrable than currently known wheeled work vehicles.

The present invention is directed towards providing such a wheeled work vehicle suitable for cutting grass and for other purposes.

According to the invention there is provided a wheeled work vehicle comprising a chassis extending between a forward end and a rearward end, two independently driven main ground engaging wheels carried on respective wheel carriers located on the chassis towards the forward end or the rearward end thereof, and spaced apart transversely relative to the normal forward direction of travel of the work vehicle, each wheel carrier carrying a corresponding electrically powered main drive motor for driving the corresponding main ground engaging wheel, each main drive motor defining a rotational drive axis about which drive is produced by the main drive motor and extending outwardly from the wheel carrier with the drive axis extending transversely relative to the normal forward direction of travel of the work vehicle, each main drive motor being of an outer transverse cross-section transversely of the corresponding drive axis thereof less than the transverse cross-section of a well of a wheel rim of the corresponding main ground engaging wheel so that the main drive motors fit substantially within the wells of the wheel rims of the respective main ground engaging wheels.

In one embodiment of the invention each main drive motor is of length in a direction parallel to its drive axis so that the main drive motor fits entirely within the well of the wheel rim of the corresponding main ground engaging wheel. In another embodiment of the invention each main drive motor is of length in a direction parallel to its drive axis so that when the main drive motor is secured to the wheel rim in the well thereof of the corresponding main ground engaging wheel a portion of the main drive motor extends out of the well towards the corresponding wheel carrier.

Preferably, the portion of each main drive motor extending out of the well of the wheel rim of the corresponding main ground engaging wheel spaces the corresponding main ground engaging wheel from the wheel carrier and/or the chassis.

Advantageously, each main drive motor comprises a coupling element rotatably driven by the main drive motor about the drive axis thereof, the coupling element being adapted for releasably securing the corresponding main ground engaging wheel thereto. Preferably, each main drive motor is adapted for securing to the corresponding wheel carrier by a securing means.

In one embodiment of the invention each main drive motor comprises a motor housing. Preferably, the motor housing of each main drive motor is secured to the corresponding wheel carrier.

Advantageously, the motor housing of each main drive motor defines the securing means by which the main drive motor is adapted for securing to the corresponding wheel carrier. Preferably, the coupling element of each main drive motor is rotatable in the motor housing thereof.

In one embodiment of the invention the coupling element of each main drive motor is mounted fast on a main drive element rotatably mounted in the motor housing thereof. Preferably, the securing means defined by the motor housing of each main drive motor is axially spaced apart from the coupling element thereof in a direction parallel to the drive axis.

In another embodiment of the invention each main drive motor comprises a braking system located therein for braking the corresponding main ground engaging wheel.

Preferably, the braking system of each main drive motor is cooperable directly or indirectly with either the corresponding main drive element or the corresponding coupling element for braking of the corresponding main ground engaging wheel.

Preferably, the braking system is configured for reducing the speed of the work vehicle (dynamic braking) and as a parking brake.

Advantageously, the braking system is hydraulically operated.

Advantageously, the braking system is mechanically operated.

Preferably, the braking system is hydraulically operated for dynamically braking the work vehicle, and is mechanically operated for operating the braking system as a parking brake.

In one embodiment of the invention the braking system is operable in response to operation of a parking brake lever, and preferably, is mechanically operated through a Bowden cable.

In one embodiment of the invention a linear motor operates the Bowden cable in response to operation of the parking brake lever.

In another embodiment of the invention the main driving motors are configured to operate in a regenerative braking mode.

Advantageously, the braking system of each main drive motor is located within the motor housing thereof.

Preferably, each main drive motor comprises a reduction gear train located therein for reducing the rotational speed of the drive applied to the main drive element thereof.

Advantageously, the reduction gear train of each main drive motor is located within the motor housing thereof. In one embodiment of the invention each wheel carrier comprises a suspension arm extending from a first end to a second end, the first end of each suspension arm being pivotally coupled to the chassis about a corresponding main transverse pivot axis extending transversely of the normal forward direction of travel of the work vehicle.

Preferably, the main drive motor of each wheel carrier is mounted on the suspension arm adjacent the second end thereof.

Advantageously, each suspension arm extends from the main transverse pivot axis in either a generally forward direction or a generally rearward direction relative to the normal forward direction of travel of the work vehicle, and preferably, the main transverse pivot axes of the respective suspension arms coincide with each other.

Preferably, each suspension arm extends from the main transverse pivot axis in the generally rearward direction to form the suspension arm as a trailing suspension arm.

Preferably, each suspension arm is connected to the chassis through a corresponding main suspension system.

Advantageously, the main suspension system of each suspension arm is connected to the suspension arm towards or adjacent the second end thereof.

In one embodiment of the invention each main suspension system comprises a spring.

Preferably, the spring of each main suspension system comprises a compression spring acting between the chassis and the corresponding suspension arm.

Advantageously, each suspension system comprises a damper element.

Advantageously, the damper element of each main suspension system comprises a pneumatic damper element and/or a hydraulic damper element.

Preferably, each suspension system comprises a shock absorber. In one embodiment of the invention each main suspension system is adjustably coupled to either or both of the corresponding suspension arm or the chassis for adjusting the vertical spacing between the drive axis defined by the corresponding main drive motor and the chassis, and preferably, each main suspension system is adjustably coupled to either or both of the corresponding suspension arm or the chassis by an adjustable coupling system.

Preferably, each main suspension system is adjustably coupled to the corresponding suspension arm.

In one embodiment of the invention the main drive motors are controllable independently of each other.

Preferably, the speed and the direction of drive produced by the main drive motors are independently controllable for driving and steering the work vehicle.

Advantageously, the main drive motors are independently controllable by at least one joystick operated controller, or a steering wheel operated controller in conjunction with a speed controller, the at least one joystick operated controller or the steering wheel operated controller being located to be accessible to a driver in a driver accommodating location defined on the chassis.

Preferably, the at least one joystick operated controller is mounted on the chassis or other part of the work vehicle in or relative to the driver accommodating location for operation by a driver of the work vehicle.

Advantageously, the at least one joystick operated controller is centrally located in the driver accommodating location, and preferably, between the opposite side edges thereof.

Preferably, the at least one joystick operated controller is located forwardly in the driver accommodating location.

In one embodiment of the invention a pair of joystick operated controllers are provided, each joystick operated controller being adapted to control a corresponding one of the main drive motors.

In another embodiment of the invention the joystick operated controllers are located in or adjacent the driver accommodating location. Preferably, the joystick operated controllers are located on respective opposite sides of the driver accommodating location.

Preferably, the driver accommodating location comprises a driver's seat.

Advantageously, the joystick operated controllers are located on respective opposite sides of the driver’s seat and forwardly thereof.

In another embodiment of the invention the joystick operated controllers are located side-by-side forwardly of the driver's seat or forwardly in the driver accommodating location.

Preferably, each joystick operated controller is located closest to the corresponding main drive motor which is controlled by that joystick operated controller.

Advantageously, the speed and the direction of drive produced by the main drive motors are independently controlled by the respective joystick operated controllers for driving and steering the work vehicle.

In one embodiment of the invention a battery compartment is provided for accommodating an electrical battery for powering the main drive motors.

Preferably, the electrical battery for powering the main drive motors is located in the battery compartment.

Preferably, the electrical battery comprises a rechargeable battery.

In one embodiment of the invention a charger is provided in the work vehicle for charging the battery from a mains electricity supply.

Preferably, each main drive motor comprises an alternating current motor or a direct current motor.

Advantageously, each main drive motor comprises a three-phase motor or a single-phase motor. In one embodiment of the invention the main drive motor comprises a permanent magnet synchronous motor. Preferably, each main drive motor comprises a rotor, and advantageously, the rotor of each main drive motor comprises one or more permanent magnets.

In another embodiment of the invention each main drive motor comprises a stator, and preferably, the stator of each main drive motor is fixed to the motor housing thereof, and advantageously, the stator of each main drive motor comprises electro-magnetic coils.

In another embodiment of the invention at least one secondary ground engaging wheel is located towards the opposite one of the forward end or the rearward end of the chassis towards which the main ground engaging wheels are located.

Preferably, the at least one secondary ground engaging wheel comprises a non-driven secondary ground engaging wheel.

Advantageously, the at least one secondary ground engaging wheel comprises a castor type ground engaging wheel.

Preferably, the at least one secondary ground engaging wheel is pivotal relative to the chassis about a corresponding substantially vertical pivot axis.

In one embodiment of the invention a pair of the secondary ground engaging wheels are provided spaced apart relative to each other transversely relative to the normal forward direction of travel of the work vehicle.

Preferably, each secondary ground engaging wheel is coupled to the chassis by a secondary suspension system.

Advantageously, the secondary suspension system is independent of the main suspension system.

In one embodiment of the invention the chassis is adapted for carrying an attachment.

Preferably, the chassis is adapted for carrying the attachment beneath the chassis. Advantageously, the attachment is located beneath the chassis intermediate the main ground engaging wheels and the at least one secondary ground engaging wheel.

Preferably, the chassis is adapted for releasable or non-releasable mounting of the attachment to the chassis.

In one embodiment of the invention the attachment comprises a mower.

Preferably, the mower comprises a mower housing and at least one blade located in or on the mower housing and rotatable about a blade rotational axis.

Advantageously, the mower comprises a rotary mower.

Preferably, the at least one blade is rotatable about a corresponding substantially vertical rotational axis.

Preferably, the rotary mower comprises at least two blades rotatable about respective corresponding blade rotational axes extending parallel to each other.

Advantageously, the blade rotational axes are spaced apart transversely relative to the normal forward direction of travel of the work vehicle.

In another embodiment of the invention at least three blades are provided rotatably mounted about respective corresponding blade rotational axes, the blade rotational axes of two of the blades being spaced apart transversely from each other and being transversely aligned in a substantially vertical transverse plane extending transversely of the normal forward direction of travel of the work vehicle, and the blade rotational axes of a third one of the blades being located either forwardly or rearward ly of the transverse plane, within which the blade rotational axes of the other two blades are transversely aligned.

Preferably, the blade rotational axis of the third blade is located intermediate respective spaced apart parallel substantially vertically extending planes extending substantially parallel to the normal forward direction of travel of the wheeled work vehicle containing the aligned blade rotational axes of the other two blades. Advantageously, the blade rotational axes of the third blade lies substantially midway between the two parallel substantially vertically extending planes extending substantially parallel to the normal forward direction of travel of the work vehicle.

Preferably, the blades of the mower are arranged in pairs, and each pair of the blades is rotatable about a corresponding one of the blade rotational axes.

In another embodiment of the invention the attachment comprises a plough blade.

In a further embodiment of the invention the attachment comprises an earth working tool.

In another embodiment of the invention the attachment comprises an agricultural tool.

In one embodiment of the invention at least one electrically powered secondary drive motor is provided for powering the attachment.

Preferably, the secondary drive motor is powered by the battery.

Preferably, the attachment is mounted on the chassis through an attachment suspension system.

Advantageously, the attachment suspension system is independent of the main suspension system.

Preferably, the attachment suspension system is independent of the secondary suspension system.

The advantages of the invention are many. A particularly important advantage of the invention is that by virtue of the fact that the main drive motors are sized for locating substantially within the wheel wells of the wheel rims of the main ground engaging wheels, a particularly compact work vehicle is provided. Due to the fact that the main drive motors are located within the wheel wells of the main ground engaging wheels, the main ground engaging wheels may be located adjacent the corresponding suspension arms with minimal spacing between the inner edge of the wheel rim and the corresponding suspension arm. Additionally, the suspension arms may be located adjacent the chassis, since there is no need to mount drive motors or gear boxes or braking systems on the inward side of the suspension arms. A further advantage of the invention is that the wheeled work vehicle is entirely electrically powered, and by appropriately sizing the rechargeable battery, the work vehicle may be configured to operate for a period of seven to ten hours between charges. Another advantage of the invention is that the wheeled work vehicle according to the invention is a particularly compact wheeled work vehicle, and when fitted with a mower is particularly suitable for mowing relatively large areas of grass, for example, public parks, football pitches, golf courses and the like. A further advantage of the invention is achieved when the wheeled work vehicle is adapted to operate with a range of attachments, as well as a mower, since in such cases, the wheeled work vehicle may be readily adapted to carry out other functions by merely changing the attachment, for example, in summer the attachment mounted on the wheeled work vehicle may be a mower for mowing parklands, football pitches, golf courses and the like, while in winter, the wheeled work vehicle may be fitted with an elongated plough blade for clearing snow.

The invention will be more clearly understood from the following description of some preferred embodiments thereof which are given by way of example only with reference to the accompanying drawings and are not intended to limit the scope of the invention in any way, in which:

Fig. 1 is a front elevational view of a wheeled work vehicle according to the invention,

Fig. 2 is a side elevational view of the wheeled work vehicle of Fig. 1 ,

Fig. 3 is a top plan view of the wheeled work vehicle of Fig. 1 ,

Fig. 4 is a side elevational view of the wheeled work vehicle of Fig. 1 with a portion of the wheeled work vehicle removed,

Fig. 5 is a side elevational view of a portion of the wheeled work vehicle of Fig. 1 ,

Fig. 6 is an enlarged side elevational view of a detail of the portion of Fig. 5 of the wheeled work vehicle of Fig. 1,

Fig. 7 is a top plan view of the detail of Fig. 6 of the wheeled work vehicle of Fig. 1 , Fig. 8 is a perspective view of a portion of the detail of Fig. 7 of the wheeled work vehicle of Fig. 1 ,

Fig. 9 is a perspective view of the detail of Fig. 8 from a different angle to that of Fig. 8 of the wheeled work vehicle of Fig. 1 ,

Fig. 10 is a partly cross-sectional top plan view of the detail of Fig. 7 of the wheeled work vehicle of Fig. 1,

Fig. 11 is a top plan view of another portion of the wheeled work vehicle of Fig. 1 ,

Fig. 12 is a cross-sectional top plan view of the portion of Fig. 11 on the line XII-XII of Fig. 2 of the wheeled work vehicle of Fig. 1 ,

Fig. 13 is a block representation of another portion of the wheeled work vehicle of Fig. 1 ,

Fig. 14 is a circuit diagram of an electrical control circuit of the wheeled work vehicle of Fig. 1 , and

Fig. 15 is an electrical control circuit of a wheeled work vehicle according to another embodiment of the invention.

Referring to the drawings, and initially to Figs. 1 to 14, there is illustrated a wheeled work vehicle according to the invention indicated generally by the reference numeral 1. The work vehicle 1 is electrically powered, and in this embodiment of the invention carries an attachment in this case a mower 2, as will be described below, and is suitable for mowing grass. However, it will be appreciated that the work vehicle 1 may be adapted for carrying any other attachment, for example, a transversely extending plough blade for clearing earth or snow, a horizontally rotatably mounted cylindrical brush, agricultural tools, for example, a series of transversely spaced apart plough blades, a harrow, for soil breaking, a rake, or any other desirable or suitable attachment. The work vehicle 1 comprises a chassis 3 extending between a forward end 5 and a rearward end 7. The chassis 3 is supported on four ground engaging wheels, namely, a pair of main ground engaging wheels 9 and a pair of secondary ground engaging wheels 10. The main ground engaging wheels 9 are driven independently of each other as will be described below and are mounted towards the rearward end 7 of the chassis 3 spaced apart transversely relative to the normal forward direction of travel of the work vehicle 1, namely, the direction of travel indicated by the arrow A. The secondary ground engaging wheels 10 in this embodiment of the invention are non-driven castor type wheels and are located towards the forward end 5 of the chassis 3 and are spaced apart transversely relative to the normal forward direction of travel of the work vehicle 1. Each secondary ground engaging wheel 10 is freely rotatably mounted on a substantially horizontally extending axle 11 carried on a carrier framework 13. The carrier framework 13 of each secondary ground engaging wheel 10 is pivotally coupled to the chassis 3 by a pivot mounting 6, which defines a substantially vertically extending pivot axis 8, about which the carrier framework 13 is freely pivotal through 360°.

The chassis 3 defines a driver accommodating location 12 on which a seat 14 is mounted towards the rear of the driver accommodating location for accommodating a driver driving the work vehicle 1. A backrest 15 extends upwardly from the rear of the seat 14, and a pair of transversely spaced apart arm rests 16 extend forwardly from the back rest 15. A roll protection frame 18 is located adjacent the rear of the driver accommodating location 12, and comprises a pair of spaced apart upstanding side members 20 extending upwardly from the chassis 3 and joined by a top cross-member 22 for protecting the driver in the event of the work vehicle 1 rolling over. Instead of or as well as the roll protection bar 18, an enclosed driver cab may be mounted on the chassis 3.

A battery compartment 25 located in a rearward housing 27 mounted on the chassis 3 houses a rechargeable electrical battery 26 for powering the work vehicle 1 as will be described in detail below. In this embodiment of the invention the battery 26 comprises a forty-eight volt battery, but may be of any suitable voltage, and will, in general, be of voltage determined by the maximum voltage requirement of the components to be powered by the battery 26. An electrical battery charger 24 is located in the rearward housing 27 for charging the battery 26 in the battery compartment 25 from a mains electricity supply. Such battery chargers will be known to those skilled in the art. In some embodiments of the invention the battery charger may be omitted, and in which case, a port would be located in the rear housing or in any other suitable part of the work vehicle 1 for connecting the battery 26 to a suitable remotely located charger.

Turning now to the main ground engaging wheels 9, and referring in particular to Figs. 5 to 10, each main ground engaging wheel 9 comprises a wheel rim 29 which defines a wheel well 30 of inner diameter D1 and of depth d. h pneumatic tyre 32 is mounted on the wheel rim 29, see Fig. 10. Each main ground engaging wheel 9 is caried on a corresponding wheel carrier, which in this embodiment of the invention comprises a trailing suspension arm 34 extending from a first end 35 to a second end 36.

Each suspension arm 34 is pivotally coupled to the chassis 3 adjacent the first end 35 thereof about a main substantially horizontally extending main transverse pivot axis 38 and extends rearwardly therefrom.

A pair of spaced apart coupling brackets 40 extending rearwardly from the chassis 3, only a part of which is illustrated in Fig. 10, carry a pivot shaft 42 which defines the main transverse pivot axis 38. The pivot shaft 42 pivotally engages bushings 44 carried in a tubular carrier member 45 welded to the corresponding suspension arm 34 adjacent the first end 35 thereof. In this embodiment of the invention the pivot shaft 42 comprises a bolt 46 extending through and between the coupling brackets 40 and through the bushings 44 in the tubular member 45. A head 47 of the bolt 46 abuts one of the coupling brackets 40 and a nut 48 on the bolt 46 is tightened on the bolt 46 to abut the other one of the coupling brackets 40 with the bolt 46 tightly secured in the coupling brackets 40 and with the corresponding suspension arm 34 pivotal on the bolt 46 about the main transverse pivot axis 38. The coupling brackets 40 of the respective suspension arms 34 are aligned so that the main transverse pivot axes 38 of the respective suspension arms 34 are aligned and coincide with each other. It will be appreciated that any suitable pivot shafts besides the bolts 46 may be used.

An electrically powered three-phase forty-eight volt alternating current permanent magnet synchronous main drive motor 50 is mounted on each suspension arm 34 adjacent the second end thereof for driving the corresponding main ground engaging wheel 9. The main drive motors 50 are powered by the battery 26 as will be described below. Each main drive motor 50 comprises a motor housing 51 having a securing means, namely, a mounting plate 53 and a substantially cylindrical side wall 55 extending from the mounting plate 53. Each main drive motor 50 is secured to the corresponding suspension arm 34 by a plurality of screws 56 which extend through bores (not shown) in a carrier plate 57 welded to the corresponding suspension arm 34 adjacent the second end 36 thereof, and in turn engage threaded bores (also not shown) in the mounting plate 53 of the corresponding main drive motor 50. A main drive element comprising a main drive shaft 58 rotatably mounted in bearings (not shown) in the motor housing 51 of each main drive motor 50 defines a rotational drive axis 60 about which the main drive shaft 58 is rotatable for producing drive from the main drive motor 50. A coupling element, in this embodiment of the invention a coupling plate 62 is mounted fast on the main drive shaft 58 of each main drive motor 50 and carries five studs 64 equi-spaced apart circumferentially around the drive axis 60 for releasably securing the corresponding main ground engaging wheel 9 to the coupling plate 62 for driving thereof. The motor housing 51 of each main drive motor 50 defines an outer cross-section transversely of the drive axis 60 thereof of an outer diameter D2 which is less than the inner diameter D1 of the wheel well 30 of the corresponding main ground engaging wheel 9, so that the main drive motors 50 extend into the wheel wells 30 of the respective main ground engaging wheels 9. The length L of each main drive motor 50 in a direction parallel to the drive axis 60 from the mounting plate 53 to the coupling plate 62 thereof is sufficiently greater than the depth d of the wheel well 30 of the corresponding main ground engaging wheel 9, so that when the main ground engaging wheel 9 is secured to the coupling plate 62 of the corresponding main drive motor 50 by the studs 64, clearance is provided between an inner edge 65 of the wheel rim 29 and inner wall 66 of the pneumatic tyre 32 of the main ground engaging wheel 9 and the corresponding suspension arm 34 and the chassis 3, in order to avoid any danger of the wheel rim 29 or the pneumatic tyre 32 of the main ground engaging wheel 9 rubbing on the corresponding suspension arm 34 or the chassis 3. Referring now to Fig. 13, each main drive motor 50 comprises a stator 67 fixedly mounted in the motor housing 51. The stator 67 of each main drive motor 50 in this case comprises electrically powered electromagnetic coils (not shown). A rotor 68 of each main drive motor 50 comprising permanent magnets (also not shown) is mounted fast on a primary drive shaft 69 of the main drive element of the corresponding main drive motor 50. The rotor 68 of each main drive motor 50 cooperates with the stator 67 thereof for driving the corresponding primary drive shaft 69. The primary drive shaft 69 of each main drive motor 50 is rotatably mounted in bearings (not shown) in the motor housing 51, and drives the main drive shaft 58 through a reduction geartrain 70 located in the corresponding motor housing 51. The reduction geartrain 70 of each main drive motor 50 is provided with a suitable reduction gear ratio for reducing the speed transmitted from the primary drive shaft 69 to the main drive shaft 58 to a suitable range of speeds for driving the corresponding main ground engaging wheel 9, and is dependent on the speed range at which the primary drive shaft 69 is driven.

A brake drum 72 located in the motor housing 51 of each main drive motor 50 is mounted fast on the main drive shaft 58 thereof. A pair of brake shoes 73 located within the brake drum 72 of each main drive motor 50 are responsive to operation of a brake pedal 74 located on a platform 75 mounted on the chassis 3 forward of the seat 14 for reducing the speed of the work vehicle, and are also responsive to a handbrake lever (not shown), but located adjacent the seat 14 for operating the brake shoes 73 as a parking brake when the work vehicle 1 is parked. The brake shoes 73 of the respective main drive motors 50 are operated hydraulically by the brake pedal 74 as a dynamic brake for reducing the speed of the work vehicle 1 and for bringing the work vehicle 1 to a halt during normal operation of the work vehicle. An hydraulic actuator located in the motor housing 51 of each main drive motor 50 acts between the corresponding pair of brake shoes 73 for progressively urging the brake shoes 73 into engagement with the brake drum 72 in response to progressive depression of the brake pedal 74. An hydraulic pipe 71 extends from the hydraulic actuator 76 of the brake shoes 73 of each main drive motor 50 through the mounting plate 53 of the corresponding main drive motor to an hydraulic pump (not shown) operated by the brake pedal 74. The hydraulic pump (not shown) is responsive to depression of the brake pedal 74 for in turn progressively pressurising the hydraulic fluid in the hydraulic actuator 76 of the respective main drive motors 50 for progressively urging the brake shoes 73 into engagement with the corresponding brake drums 72 as the brake pedal 74 is progressively depressed, for dynamic braking of the work vehicle 1.

A mechanical actuator 101 located in the brake drum 72 of each main drive motor 50 acting between the corresponding pair of brake shoes 73 mechanically operates the brake shoes 73 into engagement with the brake drum 72 for operating the brake shoes 73 as a parking brake for braking the work vehicle 1 when parked. A Bowden cable 93 coupled to the mechanical actuator 101 of each main drive motor 50 for operating the mechanical actuator 101 thereof extends from the mechanical actuator 101 through the main housing 51 and through the mounting plate 53 of the main housing 51. Each Bowden cable 93 is operated by an electrically powered linear motor (not shown), which is activated by the hand brake lever (not shown) for operating the mechanical actuators 101 of the respective main drive motors 50, for in turn urging the brake shoes 93 into engagement with the respective brake drums 72 to brake the work vehicle 1 when parked.

Returning now to the suspension arms 34, the second end 36 of each suspension arm 34 is connected to the chassis 3 by a corresponding main suspension system 78, which in this embodiment of the invention comprises a compression spring 79 and a pneumatic damper 80 located within the compressing spring 79, see Figs. 5 to 7. The compression spring 79 of each main suspension system 78 acts between a lower end stop 81 mounted on a cylinder 83 of the damper 80, and an upper end stop 84 located towards a distal end portion 86 of a piston rod 85 of the damper 80 extending from the cylinder 83 thereof. The compression spring 79 of each main suspension system 78 accommodates but dampens relative movement of the corresponding suspension arm 34 about the corresponding main transverse pivot axis 38 relative to the chassis 3, and the corresponding damper 80 dampens oscillations of the corresponding suspension arm 34 about the main transverse pivot axis 38.

Each main suspension element 78 is secured to the chassis 3 by a corresponding mounting bracket 88 coupled to the chassis 3. The distal portion 86 of the piston rod 85 of the pneumatic damper 80 extends through a bore (not shown) in the mounting bracket 88, and a pair of resilient bushings 77 located in the distal portion 86 of the piston rod 85 of the corresponding damper 80 clamp the mounting bracket 88 therebetween. Nuts 82 on a threaded portion of the distal portion 86 of the piston rod 85 acting against the upper end stop 84 on the piston rod 85 tightly clamp the corresponding mounting bracket 88 between the bushings 77 for securing the main suspension system 78 to the corresponding mounting bracket 88, and in turn to the chassis 3.

A lower end mounting 89 of each main suspension system 78 extending downwardly from the cylinder 83 of the damper 80 is secured to the second end 36 of the corresponding suspension arm 34 through an adjustable coupling system 90. The adjustable coupling system 90 of each main suspension system 78 is provided by an extension plate 91 extending rearwardly from the second end 36 of the corresponding suspension arm 34 through which three equi-spaced apart bores 92 extend, and which are selectively engageable by a coupling bolt 94 for securing the lower end mounting 89 of the main suspension system 78 to the corresponding suspension arm 34. The coupling bolt 94 pivotally engages a pivot bore (not shown) in the lower end mounting 89 of the corresponding damper 80. By selecting the bore 92 in the extension plate 91 of each suspension arm 34 to which the lower end mounting 89 of the corresponding main suspension system 78 is secured, the vertical spacing between the drive axis 60 of the main drive motor 50 of the corresponding suspension arm 34 and the chassis 3 is adjustable. This in turn permits the vertical positioning of the corresponding main ground engaging wheel 9 relative to the chassis 3 to be adjusted in order to adjust the height of the mower 2 above the ground, for in turn setting the height to which grass is to be cut by the mower. It is envisaged that in some embodiments of the invention more than three bores 92 may be provided to increase the range of the height adjustment of the mower 2 above the ground and to increase the fineness of the adjustment. However, in some embodiments of the invention the adjustable coupling system may be omitted, and only a single coupling position, namely a single bore 92 extending through the extension plate 91 of each suspension arm 34 would be provided for coupling the lower end mounting 89 of each main suspension system 78 to the corresponding suspension arm 34. Turning now to the mower 2, and referring to Figs. 1 to 4, 11 and 12, the mower 2 comprises a mower housing 95 having a top wall 96 and a peripheral side wall 97 extending around and downwardly from the outer periphery of the top wall 96 and defining a hollow interior region 98. Three pairs of cutting blades 99 located in the hollow interior region 98 of the mower housing 95 are carried on respective parallel secondary drive shafts 100 which are rotatably mounted in bearings (not shown) in the top wall 96. The secondary drive shafts 100 define respective blade rotational axes 102 about which the cutting blades 98 are rotatable in the hollow interior region 99.

Each pair of cutting blades 99 are formed by a cutting bar 104 with the corresponding secondary drive shaft 100 secured centrally to the cutting bar 104, and extending perpendicularly therefrom. Each cutting bar 104 is provided with two cutting edges 105 extending from a location adjacent the corresponding secondary drive shaft 100 to a location substantially adjacent a corresponding outer end 106 of the cutting bar 104. The cutting edges 105 of each cutting bar 104 define the respective cutting blades 99 of the pair of cutting blades thereof.

The ends 106 of each cutting bar 104 defines a circular area 107 swept by the cutting bar 104 as the cutting bar 104 rotates about the corresponding blade rotational axis 102. The secondary drive shafts 100 are located spaced apart from each other in the top wall 96 of the mower housing 95, so that the cutting areas 107 swept by the respective cutting bars 104 are spaced apart from each other in order to avoid the respective cutting bars 104 interfering with each other.

In this embodiment of the invention the blade rotational axes 102a and 102b of two of the secondary drive shafts 100a and 100b are aligned with each other in a transverse plane 108 extending transversely of the normal forward direction of travel of the wheeled work vehicle. The blade rotational axis 102c of the remaining secondary drive shaft 100, namely, the secondary drive shaft 100c, is located forwardly of the transverse plane 108, and lies in a substantially vertical plane 110 extending substantially parallel to the normal forward direction of travel of the work vehicle 1. The vertical plane 110 within which the blade rotational axis 102c lies, lies substantially midway between a pair of spaced apart vertical planes 112 extending parallel to the vertical plane 110 and containing the blade rotational axes 102a and 102b, respectively, of the secondary drive shafts 100a and 100b.

An outlet opening 114 extends through the side wall 97 of the mower housing 95 adjacent one side thereof for accommodating cut grass therethrough. The outlet opening 114 is configured for connection to a grass accommodating duct (not shown). The grass accommodating duct is connected to a grass collection hopper (not shown) into which grass from the mower 2 is delivered through the grass accommodating duct. The grass collection hopper may be mounted on any suitable location in or on the rear of the work vehicle 1. Alternatively, the mower 2 and the cutting blades 99 may be adapted to mulch the grass, which would be returned to the ground.

Four height control ground engaging wheels 115 are freely rotatable on shafts 116 carried on brackets 117 extending from the side wall 97 of the mower housing 95. Two of the height control ground engaging wheels 115 are located to the rear of the mower housing 95 on respective opposite sides thereof, and the other two height control ground engaging wheels 115 are spaced apart and are located adjacent the forward end of the mower housing 95. The height control ground engaging wheels 115 are provided to follow the contour of the ground for maintaining the mower 2, and in turn the cutting blades 99 at a substantially constant height above the ground. Although not illustrated, the height of the brackets 117 of the height control ground engaging wheels 115 are adjustable vertically upwardly and downwardly on the side wall 97 of the mower housing 95 for providing fine adjustment of the height of the mower, and in turn the height of the cutting blades 99 above the level of the ground. Although not illustrated in the drawings, the mower housing 95 is coupled to the chassis 3 to permit limited upward and downward movement of the mower housing 95 relative to the chassis, and also to permit side-to-side tilting of the mower housing 95 relative to the chassis 3, and to permit forward and rearward tilting of the mower housing 95 relative to the chassis 3.

A forty-eight volt three-phase secondary drive motor 118 mounted on the top wall 96 of the motor housing 95 and extending upwardly therefrom, drives the secondary drive shaft 100c, and the secondary drive shafts 100a and 100b are driven from the secondary drive shaft 100c through chain and sprocket drive transmissions 119 for rotating and powering the cutting blades 99. The secondary drive motor 118 is powered by the battery 26 as will be described below. In some embodiments of the invention it is envisaged that each drive shaft 100 of each pair of cutting blades 99 may be driven by a separate secondary motor 118.

Referring now to Fig. 14, the powering and control of the main drive motors 50, and the secondary drive motor 118 of the mower 2, will now be described. An electrical control circuit 120 comprising an electronic control unit 122 generally controls the operation of the work vehicle 1. Power is supplied from the battery 26 to the electrical control circuit 120 through a power distribution module 123. The main drive motors 50 and the secondary drive motor 118 of the mower 2, are powered independently of each other through respective inverters 125 and 126, which convert the forty-eight volt DC power supply from the battery 26 to a three-phase AC power supply at forty-eight volts. The main drive motors 50 are powered through the respective inverters 125, while the secondary drive motor 118 is powered through the inverter 126.

The power is supplied to the main drive motors 15 under the control of the electronic control unit 122, in response to the operation of respective joystick operated controllers 128. Each joystick operated controller 128 comprises an electronic controller 129 which is configured to produce a signal indicative of the speed at which the drive motor 50 corresponding to that joystick operated controller 128 is to be driven, and the rotational direction in which the main drive shaft 58 of that main drive motor 50 is to be rotated. The electronic control unit 122 is responsive to the signals produced by the electronic controllers 129 of the joystick operated controllers 128 for operating the corresponding inverters 125 to power the corresponding main drive motors 50 with the main drive shaft 58 of the main drive motors 50 rotating at the appropriate speed in the appropriate rotational direction.

Each joystick operated controller 128 comprises a joystick 130 extending from the electronic controller 129. The joystick operated controllers 129 are mounted on the platform 75 on respective opposite sides of the seat 14, and slightly forward of the seat 14 so that the joysticks 130 are operable by a driver sitting in the drive seat. The joystick operated controllers 128 are located on the respective sides of the seat 14 corresponding to the side of the work vehicle 1 on which the corresponding main drive motor 50 is located. In other words, the joystick operated controller 128a is located on the left-hand side of the work vehicle 1 when viewed from the rear of the work vehicle looking forwardly, and the corresponding main drive motor 50a, which is controlled by the joystick operated controller 128a, is also located on the lefthand side of the work vehicle 1. The joystick operated controller 128b is located on the right-hand side of the work vehicle 1 and the corresponding main drive motor 50b, which is controlled by the joystick operated controller 128b is located on the right-hand side of the work vehicle 1.

The joysticks 130 are mounted relative to the driver’s seat 14, so that when each joystick 130 is urged forwardly from a substantially vertically extending zero speed position, the electronic control unit 122 controls the corresponding main drive motor 50 through the corresponding inverter 125 to produce drive on the main drive shaft 58 thereof to rotate the corresponding main ground engaging wheel 9 to drive the work vehicle 1 in a forward direction, and when each joystick 130 is urged rearwardly from the zero speed position, the electronic control unit 122 controls the corresponding main drive motor 50 to produce drive on the main drive shaft 58 thereof to rotate the main drive shaft 58 in the reverse direction for in turn rotating the corresponding main ground engaging wheel 9 for driving the work vehicle 1 in reverse. The more each joystick 130 is urged forwardly from the zero speed position, the greater will be the electrical current supplied to the corresponding main drive motor 50 through the corresponding inverter 125 under the control of the electronic control unit 122 in order to power the corresponding main drive motor 50 to drive the corresponding main ground engaging wheel 9 faster for driving the work vehicle faster in the forward direction. Similarly, the more each joystick 130 is urged rearwardly from the zero speed position, the greater will be the electrical current supplied through the corresponding inverter 125 under the control of the electronic control unit 122 to the corresponding main drive motor 50 in order to rotate the corresponding main ground engaging wheel 9 faster in reverse.

Accordingly, the work vehicle 1 remains stationary while the joysticks 130 are both in the zero speed position. To drive the work vehicle 1 forwardly dead-ahead, both joysticks 130 are urged forwardly by the same amount from the zero speed position, and to drive the work vehicle 1 in reverse, both joysticks 130 are urged rearwardly from the zero speed position by the same amount. When it is desired to turn the work vehicle 1 to the left in a forward direction, the left-hand joystick 130a is urged rearwardly from its current position to reduce the speed of the left-hand main drive motor 50a, while the right-hand joystick 130b is urged forwardly from its current position to increase the speed of the right-hand main drive motor 50b, and vice versa for steering the work vehicle 1 to the right in a forward direction. Where it is desired to operate the work vehicle 1 to turn in its own area, which is commonly referred to as a zero turn, one of the joysticks 130 is urged forwardly from the zero speed position, while the other one of the joysticks 130 is urged the same distance rearwardly from the zero speed position.

A brake pedal sensor 131 monitors the degree of depression of the brake pedal 74 and produces a signal indicative of the degree to which the brake pedal 74 is depressed from a rest non-braking position. The electronic control unit 122 reads the signal produced by the brake pedal sensor 131 and on the signal read from the brake pedal sensor 131 being indicative of the brake pedal 74 being depressed, the electronic control unit 122 operates the inverters 125 and the main drive motors 50 in a regenerative braking mode to brake the main ground engaging wheels 9 and to charge the battery 26. The degree of regenerative braking is determined by the degree of depression of the brake pedal 74 from the rest, nonbraking position. The greater the degree of depression of the brake pedal 74, the greater will be the degree of the regenerative braking. The brake pedal 74 is allowed an initial predefined degree of depression from the rest, non-braking position before the hydraulic pump (not shown) which activates the hydraulic actuators 76 of the brake shoes 73 in the respective main drive motors 50 is operated by the brake pedal 74. Once the brake pedal 74 has been depressed through the initial predefined degree of depression, the brake pedal 74 engages the hydraulic pump (not shown) thereby which in turn activating the hydraulic pump which in turn operates the hydraulic actuators 76 of the respective main drive motors 50 to brake the work vehicle in convention fashion. During hydraulic braking of the work vehicle 1, the electronic control unit 122 continues to operate the inverters 125 and the two main drive motors 50 in the regenerative braking mode until the brake pedal 74 has been released.

A visual display screen 132, and a keypad 133 are located in a control panel 134 for displaying information relative to the operation of the work vehicle 1, for example, the ground speed of the work vehicle 1 , and for inputting data and instructions to the electronic control unit 122.

The electronic control unit 122 controls the operation of the secondary drive motor 118 for powering the cutting blades 99. The electronic control unit 122 may be adapted to automatically activate the secondary drive motor 118 in response to either one of the main drive motors 50 being operated to drive the work vehicle 1 in a forward direction, or alternatively, the electronic control unit 122 may be programmed to control the secondary drive motor 118 from inputs from the control panel 134, for example, from a switch or a joystick located in the control panel 134 or through instructions inputted through the keypad 133.

In use, with the battery 26 appropriately charged, a driver sits on the seat 14 and operates the work vehicle 1 by operating the joysticks 130 for driving the work vehicle 1 forwardly or in reverse or to turn the work vehicle 1 to the right or to the left. Additionally, the driver may operate the work vehicle 1 to turn in its own area by urging one of the joysticks 130 forwardly while the other one of the joysticks 130 is urged the same distance rearwardly. The driver may select how and when the secondary drive motor 118 is to be powered by inputting appropriate instructions to the electronic control unit 122 through the keypad 133 or through the control panel 134. Either the electronic control unit 122 may be programmed to operate the secondary drive motor 118 at all time while either one of the main drive motors 50 is being operated to drive the work vehicle in a forward direction, or the driver may select an alternative protocol for operating the secondary drive motor 118 by inputting appropriate data through the keypad 133 of the control panel 134.

To brake the work vehicle 1, the driver depresses the foot pedal 74, and depending on the degree of depression of the foot pedal, the braking of the work vehicle 1 may be carried out in regenerative braking mode entirely, or if the brake pedal has been depressed beyond the initial predefined degree of depression, the brake shoes 73 are operated by the hydraulic actuators 76 of the respective main drive motors 50. When the work vehicle 1 is parked, the hand brake lever is operated to operate the Bowden cables 93 to in turn operate the mechanical actuator 101 for urging the brake shoes 73 into engagement with the respective brake drums 72 of the respective main drive motors.

Referring now to Fig. 15 there is illustrated a block representation of an electrical control circuit indicated generally by the reference numeral 140 of a wheeled work vehicle according to another embodiment of the invention. The wheeled work vehicle in this embodiment of the invention is similar to the wheeled work vehicle 1 described with reference to Figs. 1 to 14, and similar components are identified by the same reference numerals. The only difference between the wheeled work vehicle of this embodiment of the invention and the wheeled work vehicle 1 of Figs. 1 to 14 is in the electrical control circuit for controlling operation of the main drive motors 50 and the secondary drive motor 118. In this embodiment of the invention the electrical control circuit 140 is substantially similar to the electrical control circuit 120 of the work vehicle 1 and similar components are identified by the same reference numerals. In this embodiment of the invention the control of the main drive motors 50 is controlled by a combination of a steering wheel 141 and an accelerator foot pedal 142. An angle sensor 144 monitors the degree of rotation of the steering wheel from a central dead-ahead position, and outputs a signal indicative of the angular rotation of the steering wheel from the central dead-ahead position to each side thereof, which is read by the electronic control unit 122. The accelerator foot pedal 142 operates a proportional electrical switch 145 which produces a signal indicative of the degree of depressing of the accelerator foot pedal 142. The signal from the proportional electrical switch 145 is read by the electronic control unit 122. The electronic control unit 122 is programmed to operate the main drive motors 50 in response to the signals read from the angle sensor 144 of the steering wheel 141 and from the proportional electronic switch 145 of the accelerator foot pedal 142. From the signals read from the angle sensor 144 and the proportional electronic switch 142 the electronic control unit 122 determines the speed and direction of rotation at which the main shafts 58 of the respective main drive motors 50 should be driven.

When the steering wheel is maintained in the central dead-ahead position, the electronic control unit 122 controls the speed of the main drive shafts 58 of the main drive motors 50 solely in response to the signal read from the proportional electrical switch 145. The electronic control unit 122 operates the main drive motors 50 to drive the corresponding ground engaging wheels 9 at the same speed, which is determined by the degree to which the accelerator foot pedal 142 is depressed. The greater the degree of depression of the accelerator foot pedal 142, the faster the ground engaging wheels 9 are driven. When the steering wheel is rotated to the left or the right of the central dead-ahead position, the electronic control unit 122 controls the inverters 125 to maintain the speed of the work vehicle 1 in response to the degree of depression of the accelerator foot pedal 142, and alters the relative speeds of the main drive motors 50 to affect turning of the vehicle by the amount by which the steering wheel 141 is rotated in the left-hand or right-hand directions from the central dead-ahead position. Rotating the steering wheel to the left from the central dead-ahead position results in the electronic control unit 122 operating the inverters 125 to reduce the speed of the left-hand main drive motor 50a while increasing the speed of the righthand main drive motor 50b, and vice versa, when the steering wheel 141 is rotated to the right from the central dead-ahead position. The degree of reduction in the speed of one of the main drive motors 50, and the degree of the increase in the speed of the other one of the main drive motors 50 is dependent on the angle through which the steering wheel 141 is rotated to the left or to the right from the central dead- ahead position.

To reverse the work vehicle, the steering wheel 141 is rotated through 180° from the central dead-ahead position and steering of the vehicle when reversing is substantially similar to that described for steering of the vehicle when driven forwardly.

Otherwise, the work vehicle with the electrical control circuit 140 and its operation is similar to that described with reference to the work vehicle 1 described with reference to Figs. 1 to 14. While the work vehicles have been described as comprising a mower, it will be readily apparent to those skilled in the art that the work vehicles may be provided with many other attachments, for example, earth or vegetation working or treating device. For example, it is envisaged that instead of providing a mower, an earth working device, for example, a plough blade, a harrow or the like, may be secured to and beneath the chassis in place of the mower. It is also envisaged that in some embodiments of the invention a brush or a scraper or other ground sweeping or scraping devices may be secured to and beneath the chassis in place of the mower for clearing snow. It is also envisaged that the chassis would be adapted to receive different types of earth and vegetation working or treating devices or implements. It is also envisaged that in some embodiments of the invention a snowplough may be mounted on the chassis adjacent the forward end thereof of the work vehicles according to the invention for clearing snow. It is also envisaged that a rotatably mounted cylindrical brush may be mounted on the chassis adjacent the forward end thereof but mounted rearwardly of the snowplough for bushing snow and other debris which may remain after the snowplough. Typically, such a cylindrical brush would be powered by an electrical motor powered from the battery of the wheeled work vehicle through the electronic control unit. Alternatively, in some embodiments of the invention it is envisaged that an elongated plough blade may be located beneath the chassis in place of the mower, and a cylindrical rotatably mounted brush may also be located beneath the chassis to the rear of the plough blade for clearing snow or' indeed other debris from the ground. In cases where a cylindrical rotatably mounted brush is located beneath the chassis in place of the mower, it is envisaged that the rotatably mounted cylindrical brush would be driven by an electrically powered motor powered by the battery.

While the work vehicles have been described as comprising a pair of secondary ground engaging wheels, in some embodiments of the invention a single secondary ground engaging wheel may be provided centrally of the chassis. Needless to say, other suitable secondary ground engaging wheels besides castor wheels may be provided.

It is also envisaged that in some embodiments of the invention the main ground engaging wheels may be located towards the forward end of the chassis, while the one or the pair of secondary ground engaging wheels may be located to the rear of the chassis.

It is also envisaged that instead of the suspension arms being configured as being trailing suspension arms, the suspension arms may extend forwardly from the respective main pivot axes. While the suspension system of the suspension arms has been described as being coupled to the respective suspension arms adjacent the second ends of the suspension arms, it will be appreciated that the suspension system may be connected to the suspension arms at any suitable location between the first and second ends thereof. Additionally, while the suspension system has been described as being adjustably connected to the suspension arms, it is envisaged in some embodiments of the invention that the suspension systems may not be adjustably connected to the suspension arms. In other embodiments of the invention it is envisaged that the suspension systems may be adjustably connected to the chassis, while in other embodiments of the invention it is envisaged that the suspension systems may not be adjustably connected to either the suspension arms or to the chassis. Needless to say, while the suspension system has been described as being adjustably connected to the suspension arms by a specific adjustable connection, the suspension systems may be connected to the respective suspension arms by any other adjustable means. It is also envisaged that in some embodiments of the invention any number of bores may be provided in the extension plate extending from the respective suspension arms, more or less than three bores. By increasing the number of bores extending through the extension plate, the range of the adjustability available would be increased, and/or additionally, the fineness of the adjustment would be increased. It is also envisaged that in some embodiments of the invention the suspension arms may be dispensed with, and the main drive motors would be secured to wheel carriers integrally formed with the chassis.

While the wheeled work vehicles have been described as comprising an onboard charger, while this is desirable it is not essential, and in some embodiments of the invention the onboard charger may be dispensed with and a charging port would be provided on the work vehicles for connecting to an external charger for charging the battery.

While the battery has been described as comprising a forty-eight volt battery, it will be readily apparent to those skilled in the art that the battery may be of any suitable or desirable voltage, and in general, it is envisaged that the voltage of the battery will be determined by the operating voltage or voltages required by the various components of the work vehicle being powered by the battery, and in general, the voltage of the battery will be determined by the component which requires the highest voltage.

Needless to say, it will be appreciated that the main and secondary drive motors, while they have been described as comprising forty-eight volt motors, the main and secondary drive motors may be of any other suitable voltage. It will also be appreciated that the main and secondary drive motors, while they have been described as being AC motors, may be provided as DC motors. It is also envisaged that the main and secondary drive motors may also be provided as single phase-motors instead of being provided as three-phase motors.

While the mower has been described as being powered by a single secondary drive motor, it is envisaged that more than one secondary drive motor may be provided, whereby each drive shaft of each cutting blade or each pair of cutting blades would be powered separately by a corresponding secondary drive motor.

It is also envisaged that each drive shaft of the mower instead of terminating in a pair of cutting blades, may terminate in a single cutting blade, in other words, each drive shaft would carry a single cutting blade.

While the height of the motor above the ground has been described as being adjustable by virtue of adjusting the coupling of the suspension systems to the respective suspension arms, it is envisaged that in some embodiments of the invention the height adjustment of the mower above the ground would be carried out solely by adjusting the height of the height control ground engaging wheels of the mower. Needless to say, in some embodiments of the invention the height adjustment of the mower above the ground may be controlled solely by the adjustment of the suspension arms. It is also envisaged that an electronic control system may be provided for adjusting the height of the mower above the ground, whereby one or more sensors would be located on the mower housing to monitor the height of the mower housing above the ground and the mower would be mounted to the chassis through a control system that would permit up and down movement and tilting movement of the mower housing relative to the chassis. The control system would be responsive to the sensors on the mower for maintaining the mower at a selectable predefined height above the ground.

It is also envisaged that instead of the joystick operated controllers for controlling the speed of the main drive motors being mounted on the chassis, the joystick operated controllers may be mounted on the arm rests of the seat for the driver in the driver accommodating location or in any other suitable location. In other embodiments of the invention the joystick operated controllers may be located side-by-side in front of the driver’s seat. Additionally, while the mower has been described as comprising three pairs of cutting blades, any number of cutting blades may be provided, from one cutting blade upwards, provided that the cutting blade or blades are balanced in order to avoid any "out of balance” moments being generated by the rotational axis of the cutting blades. Needless to say, any suitable means for mounting the housing of each main drive motor to the corresponding suspension arm may be provided, and where the housing of each main drive motor is secured to the corresponding suspension arm, any number of bolts may be used.

Claims

1. A wheeled work vehicle comprising a chassis extending between a forward end and a rearward end, two independently driven main ground engaging wheels carried on respective wheel carriers located on the chassis towards the forward end or the rearward end thereof, and spaced apart transversely relative to the normal forward direction of travel of the work vehicle, each wheel carrier carrying a corresponding electrically powered main drive motor for driving the corresponding main ground engaging wheel, each main drive motor defining a rotational drive axis about which drive is produced by the main drive motor and extending outwardly from the wheel carrier with the drive axis extending transversely relative to the normal forward direction of travel of the work vehicle, each main drive motor being of an outer transverse cross-section transversely of the corresponding drive axis thereof less than the transverse cross-section of a well of a wheel rim of the corresponding main ground engaging wheel so that the main drive motors fit substantially within the wells of the wheel rims of the respective main ground engaging wheels.

2. A wheeled work vehicle as claimed in Claim 1 in which each main drive motor is of length in a direction parallel to its drive axis so that the main drive motor fits entirely within the well of the wheel rim of the corresponding main ground engaging wheel.

3. A wheeled work vehicle as claimed in Claim 1 in which each main drive motor is of length in a direction parallel to its drive axis so that when the main drive motor is secured to the wheel rim in the well thereof of the corresponding main ground engaging wheel a portion of the main drive motor extends out of the well towards the corresponding wheel carrier.

4. A wheeled work vehicle as claimed in Claim 3 in which the portion of each main drive motor extending out of the well of the wheel rim of the corresponding main ground engaging wheel spaces the corresponding main ground engaging wheel from the wheel carrier and/or the chassis.

5. A wheeled work vehicle as claimed in any preceding claim in which each main drive motor comprises a coupling element rotatably driven by the main drive motor about the drive axis thereof, the coupling element being adapted for releasably securing the corresponding main ground engaging wheel thereto.

6. A wheeled work vehicle as claimed in any preceding claim in which each main drive motor is adapted for securing to the corresponding wheel carrier by a securing means.

7. A wheeled work vehicle as claimed in any preceding claim in which each main drive motor comprises a motor housing.

8. A wheeled work vehicle as claimed in Claim 7 in which the motor housing of each main drive motor is secured to the corresponding wheel carrier.

9. A wheeled work vehicle as claimed in Claim 7 or 8 in which the motor housing of each main drive motor defines the securing means by which the main drive motor is adapted for securing to the corresponding wheel carrier.

10. A wheeled work vehicle as claimed in any of Claims 7 to 9 in which the coupling element of each main drive motor is rotatable in the motor housing thereof.

11. A wheeled work vehicle as claimed in any of Claims 7 to 10 in which the coupling element of each main drive motor is mounted fast on a main drive element rotatably mounted in the motor housing thereof.

12. A wheeled work vehicle as claimed in any of Claims 7 to 11 in which the securing means defined by the motor housing of each main drive motor is axially spaced apart from the coupling element thereof in a direction parallel to the drive axis.

13. A wheeled work vehicle as claimed in any preceding claim in which each main drive motor comprises a braking system located therein for braking the corresponding main ground engaging wheel.

14. A wheeled work vehicle as claimed in Claim 13 in which the braking system of each main drive motor is cooperable directly or indirectly with either the corresponding main drive element or the corresponding coupling element for braking of the corresponding main ground engaging wheel.

15. A wheeled work vehicle as claimed in Claim 13 or 14 in which the braking system is configured for reducing the speed of the work vehicle (dynamic braking) and as a parking brake.

16. A wheeled work vehicle as claimed in any of Claims 13 to 15 in which the braking system is hydraulically operated.

17. A wheeled work vehicle as claimed in any of Claims 13 to 16 in which the braking system is mechanically operated.

18. A wheeled work vehicle as claimed in any of Claims 13 to 17 in which the braking system of each main drive motor is located within the motor housing thereof.

19. A wheeled work vehicle as claimed in any preceding claim in which each main drive motor comprises a reduction gear train located therein for reducing the rotational speed of the drive applied to the main drive element thereof.

20. A wheeled work vehicle as claimed in Claim 19 in which the reduction gear train of each main drive motor is located within the motor housing thereof.

21. A wheeled work vehicle as claimed in any preceding claim in which each wheel carrier comprises a suspension arm extending from a first end to a second end, the first end of each suspension arm being pivotally coupled to the chassis about a corresponding main transverse pivot axis extending transversely of the normal forward direction of travel of the work vehicle.

22. A wheeled work vehicle as claimed in Claim 21 in which the main drive motor of each wheel carrier is mounted on the suspension arm adjacent the second end thereof.

23. A wheeled work vehicle as claimed in Claim 21 or 22 in which each suspension arm extends from the main transverse pivot axis in either a generally forward direction or a generally rearward direction relative to the normal forward direction of travel of the work vehicle, and preferably, the main transverse pivot axes of the respective suspension arms coincide with each other.

24. A wheeled work vehicle as claimed in any of Claims 21 to 23 in which each suspension arm extends from the main transverse pivot axis in the generally rearward direction to form the suspension arm as a trailing suspension arm.

25. A wheeled work vehicle as claimed in any preceding claim in which each suspension arm is connected to the chassis through a corresponding main suspension system.

26. A wheeled work vehicle as claimed in Claim 25 in which the main suspension system of each suspension arm is connected to the suspension arm towards or adjacent the second end thereof.

27. A wheeled work vehicle as claimed in Claim 25 or 26 in which each main suspension system comprises a spring.

28. A wheeled work vehicle as claimed in Claim 27 in which the spring of each main suspension system comprises a compression spring acting between the chassis and the corresponding suspension arm.

29. A wheeled work vehicle as claimed in any of Claims 25 to 28 in which each suspension system comprises a damper element.

30. A wheeled work vehicle as claimed in Claim 29 in which the damper element of each main suspension system comprises a pneumatic damper element and/or a hydraulic damper element.

31. A wheeled work vehicle as claimed in any of Claims 25 to 30 in which each suspension system comprises a shock absorber.

32. A wheeled work vehicle as claimed in any of Claims 25 to 31 in which each main suspension system is adjustably coupled to either or both of the corresponding suspension arm or the chassis for adjusting the vertical spacing between the drive axis defined by the corresponding main drive motor and the chassis, and preferably, each main suspension system is adjustably coupled to either or both of the corresponding suspension arm or the chassis by an adjustable coupling system.

33. A wheeled work vehicle as claimed in Claim 32 in which each main suspension system is adjustably coupled to the corresponding suspension arm.

34. A wheeled work vehicle as claimed in any preceding claim in which the main drive motors are controllable independently of each other.

35. A wheeled work vehicle as claimed in Claim 34 in which the speed and the direction of drive produced by the main drive motors are independently controllable for driving and steering the work vehicle.

36. A wheeled work vehicle as claimed in Claim 34 or 35 in which the main drive motors are independently controllable by at least one joystick operated controller, or a steering wheel operated controller in conjunction with a speed controller, the at least one joystick operated controller or the steering wheel operated controller being located to be accessible to a driver in a driver accommodating location defined on the chassis.

37. A wheeled work vehicle as claimed in Claim 36 in which the at least one joystick operated controller is mounted on the chassis or other part of the work vehicle in or relative to the driver accommodating location for operation by a driver of the work vehicle.

38. A wheeled work vehicle as claimed in Claim 36 or 37 in which the at least one joystick operated controller is centrally located in the driver accommodating location, and preferably, between the opposite side edges thereof.

39. A wheeled work vehicle as claimed in any of Claims 36 to 38 in which the at least one joystick operated controller is located forwardly in the driver accommodating location.

40. A wheeled work vehicle as claimed in any of Claims 36 to 39 in which a pair of joystick operated controllers are provided, each joystick operated controller being adapted to control a corresponding one of the main drive motors.

41. A wheeled work vehicle as claimed in Claim 40 in which the joystick operated controllers are located in or adjacent the driver accommodating location.

42. A wheeled work vehicle as claimed in Claim 40 or 41 in which the joystick operated controllers are located on respective opposite sides of the driver accommodating location.

43. A wheeled work vehicle as claimed in any of Claims 40 to 42 in which the driver accommodating location comprises a driver’s seat.

44. A wheeled work vehicle as claimed in Claim 43 in which the joystick operated controllers are located on respective opposite sides of the driver’s seat and forwardly thereof.

45. A wheeled work vehicle as claimed in any of Claims 40 to 44 in which the joystick operated controllers are located side-by-side forwardly of the driver’s seat or forwardly in the driver accommodating location.

46. A wheeled work vehicle as claimed in any of Claims 40 to 45 in which each joystick operated controller is located closest to the corresponding main drive motor which is controlled by that joystick operated controller.

47. A wheeled work vehicle as claimed in any of Claims 40 to 46 in which the speed and the direction of drive produced by the main drive motors are independently controlled by the respective joystick operated controllers for driving and steering the work vehicle.

48. A wheeled work vehicle as claimed in any preceding claim in which a battery compartment is provided for accommodating an electrical battery for powering the main drive motors.

49. A wheeled work vehicle as claimed in Claim 48 in which the electrical battery for powering the main drive motors is located in the battery compartment.

50. A wheeled work vehicle as claimed in Claim 48 or 49 in which the electrical battery comprises a rechargeable battery.

51. A wheeled work vehicle as claimed in any of Claims 48 to 50 in which a charger is provided in the work vehicle for charging the battery from a mains electricity supply.

52. A wheeled work vehicle as claimed in any preceding claim in which each main drive motor comprises an alternating current motor or a direct current motor.

53. A wheeled work vehicle as claimed in any preceding claim in which each main drive motor comprises a three-phase motor or a single-phase motor.

54. A wheeled work vehicle as claimed in any preceding claim in which the main drive motor comprises a permanent magnet synchronous motor.

55. A wheeled work vehicle as claimed in any preceding claim in which at least one secondary ground engaging wheel is located towards the opposite one of the forward end or the rearward end of the chassis towards which the main ground engaging wheels are located.

56. A wheeled work vehicle as claimed in Claim 55 in which the at least one secondary ground engaging wheel comprises a non-driven secondary ground engaging wheel.

57. A wheeled work vehicle as claimed in Claim 55 or 56 in which the at least one secondary ground engaging wheel comprises a castor type ground engaging wheel.

58. A wheeled work vehicle as claimed in any of Claims 55 to 57 in which the at least one secondary ground engaging wheel is pivotal relative to the chassis about a corresponding substantially vertical pivot axis.

59. A wheeled work vehicle as claimed in any of Claims 55 to 58 in which a pair of the secondary ground engaging wheels are provided spaced apart relative to each other transversely relative to the normal forward direction of travel of the work vehicle.

60. A wheeled work vehicle as claimed in any of Claims 55 to 59 in which each secondary ground engaging wheel is coupled to the chassis by a secondary suspension system.

61. A wheeled work vehicle as claimed in any of Claims 55 to 60 in which the secondary suspension system is independent of the main suspension system.

62. A wheeled work vehicle as claimed in any preceding claim in which the chassis is adapted for carrying an attachment.

63. A wheeled work vehicle as claimed in Claim 62 in which the chassis is adapted for carrying the attachment beneath the chassis.

64. A wheeled work vehicle as claimed in Claim 62 or 63 in which the attachment is located beneath the chassis intermediate the main ground engaging wheels and the at least one secondary ground engaging wheel.

65. A wheeled work vehicle as claimed in any of Claims 62 to 64 in which the chassis is adapted for releasable or non-releasable mounting of the attachment to the chassis.

66. A wheeled work vehicle as claimed in any of Claims 62 to 65 in which the attachment comprises a mower.

67. A wheeled work vehicle as claimed in Claim 66 in which the mower comprises a mower housing and at least one blade located in or on the mower housing and rotatable about a blade rotational axis.

68. A wheeled work vehicle as claimed in Claim 66 or 67 in which the mower comprises a rotary mower.

69. A wheeled work vehicle as claimed in Claim 68 in which the at least one blade is rotatable about a corresponding substantially vertical rotational axis.

70. A wheeled work vehicle as claimed in Claim 69 in which the rotary mower comprises at least two blades rotatable about respective corresponding blade rotational axes extending parallel to each other.

71. A wheeled work vehicle as claimed in Claim 70 in which the blade rotational axes are spaced apart transversely relative to the normal forward direction of travel of the work vehicle.

72. A wheeled work vehicle as claimed in Claim 70 or 71 in which at least three blades are provided rotatably mounted about respective corresponding blade rotational axes, the blade rotational axes of two of the blades being spaced apart transversely from each other and being transversely aligned in a substantially vertical transverse plane extending transversely of the normal forward direction of travel of the work vehicle, and the blade rotational axes of a third one of the blades being located either forwardly or rearwardly of the transverse plane, within which the blade rotational axes of the other two blades are transversely aligned.

73. A wheeled work vehicle as claimed in Claim 72 in which the blade rotational axis of the third blade is located intermediate respective spaced apart parallel substantially vertically extending planes extending substantially parallel to the normal forward direction of travel of the wheeled work vehicle containing the aligned blade rotational axes of the other two blades.

74. A wheeled work vehicle as claimed in Claim 73 in which the blade rotational axes of the third blade lies substantially midway between the two parallel substantially vertically extending planes extending substantially parallel to the normal forward direction of travel of the work vehicle.

75. A wheeled work vehicle as claimed in any of Claims 69 to 74 in which the blades of the mower are arranged in pairs, and each pair of the blades is rotatable about a corresponding one of the blade rotational axes.

76. A wheeled work vehicle as claimed in any of Claims 62 to 65 in which the attachment comprises a plough blade.

77. A wheeled work vehicle as claimed in any of Claims 62 to 65 in which the attachment comprises an earth working tool.

78. A wheeled work vehicle as claimed in any of Claims 62 to 65 in which the attachment comprises an agricultural tool.

79. A wheeled work vehicle as claimed in any of Claims 62 to 78 in which at least one electrically powered secondary drive motor is provided for powering the attachment.

80. A wheeled work vehicle as claimed in Claim 79 in which the secondary drive motor is powered by the battery.

81. A wheeled work vehicle as claimed in any of Claims 62 to 80 in which the attachment is mounted on the chassis through an attachment suspension system.

82. A wheeled work vehicle as claimed in Claim 81 in which the attachment suspension system is independent of the main suspension system.

83. A wheeled work vehicle as claimed in Claim 81 or 82 in which the attachment suspension system is independent of the secondary suspension system.